Continuous press

ABSTRACT

A CONTINUOUS PRESS COMPRISES TWO CONVEYOR BELTS SERVING TO PRESS AND CONVEY BETWEEN THEM A PRODUCT IN THE SHAPE OF A PLATE OR THE LIKE AND TO SUBJECT SAID PRODUCT TO A HYDRAULIC OR PNEUMATIC PRESSURE, IN WHICH THE TWO ADJACENT FLIGHTS OF THE BELTS PASS THROUGH A PRESSURE CHAMBER THAT SURROUNDS SAID FLIGHTS IN THE TRANSVERSE DIRECTION, SAID CHAMBER HAVING ONE ENTERING OPENING AND ONE EXIT OPENING FOR THE SAID FLIGHTS.

Nov. 16', 1971 TORELLI ETAL 3,620,158

' ,commupus PRESS Filed July 11, 1969 2 Sheets-Sheet 1 1 Fig.1 v

United States Patent ()1 ice 3,620,158 CONTINUOUS PRESS Aldo Torelli and Andr Jacquemet, Grand-Laney, Geneva,

Switzerland, assiguors to Sandvikens Jernverks Aktiebolag, Sandviken, Sweden Filed July 11, 1969, Ser. No. 840,928 Claims priority, application Switzerland, July 12, 1968, 10,473/ 68 Int. Cl. 1530b /04 U.S. Cl. 100-154 2 Claims ABSTRACT OF THE DISCLOSURE A continuous press comprises two conveyor belts serving to press and convey between them a product in'the shape of a plate or the like and to subject said product to a hydraulic or pneumatic pressure, in which the two adjacent flights of the belts pass through a pressure chamberthat surrounds said flights in the transverse direction, said chamber having one entering opening and one exit opening for the said flights.

This invention relates to continuous presses employing pressure chamber means for urging two parallel conveyor flights toward each other, and is concerned with the provision of improved means for minimizing leakage of pressure fluid between the pressure chamber means and said conveyor flights.

In the manufacture of certain products having the form of plates, such for instance as wood fiber boards, it is customary to use a press comprising two conveyor belts. A flight on one belt is placed alongside a flight on the other belt, the flights being substantially parallel to each other and somewhat spaced from each other, so as to define a slit between them in which slit the product is transported, when the belts move in appropriate direction and at equal speeds. During this transport the material is subjected to pressure from a pressure device comprising a pressure chamber at the rear side of each of the adjacent belt flights, each pressure chamber extending along the surface of the adjacent flight. The pressure chambers are closed except for the side that faces the belts, which side is open, and in this way a fluid pressure medium such as a gas or liquid, which is introduced in known manner into the chambers, exerts a pressure on the belts, thereby compressing the article between them. Pressure may be adopted in order to reduce the thickness of a sheet-shaped material, and, also, it may-during simultaneous heat treatment of the productserve to counteract such internal steam pressure in the product that arises because of the heating, thereby preventing the product from falling to pieces under the influence of said internal pressure.

The invention is concerned with a continuous press of the type just described, and has for its purpose to eliminate certain problems connected with the tightenings that are placed between the pressure chambers and the belts in order to reduce leakage of fluid pressure medium. The expression tightenings as used herein tends to include known leakage barriers, such for example, as gaskets. In the previous type of press each pressure chamber has two transverse and two longitudinal edges along which gaskets or other tightenings have to be provided. These tightenings have a considerable length, and even if they are eflicient and exhibit only a small leakage per length unit, there will be a relatively great total leakage, which means losses of pressure medium, and moreover it means that the available maximum pressure is lowered.

This invention provides the improvement that instead of a separate pressure chamber along each of the two adjacent belt flights there is provided a single pressure 3,620,158 Patented Nov. 16, 1971 chamber that embraces both of the adjacent flights. The belts enter into the chamber at a slit in a chamber wall and pass out from the chamber at another slit in an opposed wall. The advantage of this arrangement is that the longitudinal tightenings are eliminated, the total length of the tightenings thus being substantially reduced. In these presses the treatment zone has often a length that is twice the width of the belt. The elimination of the longitudinal tightenings then reduces the total tightening length by /3.

Another advantage, in case frictional gaskets are used, is that the braking effect on the belt of the friction from the gaskets is reduced.

The invention will now be further described, with reference to the appended drawings, in which,

FIG. 1 is a longitudinal section of a press according to the invention;

FIG. 2 is a section on the line II-II of FIG. 1;

FIG. 3 is a longitudinal section of another embodiment of the press of the present invention;

FIG. 4 is a section on the line IVIV of FIG. 3;

FIG. 5 is a section on the line V-V of FIG. 3; and

FIGS. 6-9 show different types of gaskets that can be used to restrain leakage of pressure fluid from between the edges of the slits and the conveyor flights.

The continuous press shown in FIGS. 1 and 2 comprises two endless conveyor belts 1 and 2, for instance of steel, driven at the same speed by driving rolls 3 and 4 respectively. A product 5 to be treated, in the form of a plate, is introduced continuously between the rectilinear flights of the belts 1 and 2, which are arranged to convey the product between them under pressure across a chamber 6 into which is fed a fluid pressure medium, for instance air with a pressure supplied through a feed pipe 7 from a source 8.

As is illustrated in FIG. 2, the chamber 6 comprises an upper wall 9, a lower wall 10 and two side walls 11 and 12, which on all sides surround the adjacent flights of the belts 1 and 2, conveying the product 5. Moreover, as FIG. 1 shows, there are two transverse walls 13 and 14 limiting the chamber at its ends. The wall 13 situated at one end of the chamber 6 has an opening 15 of rectangular shape, through which opening the belts with the product betweenthem enter; and, at the other end of the chamber, there is an opening 16, also of a rectangular shape, through which the belts leave the chamber.

Gaskets 17, 18 and 19, 20, which are schematically illustrated, are mounted on the walls 13 and 14 along the openings and serve to prevent the leakage of pressure fluid from the chamber.

In the embodiment described above, it is presumed that the width of the belts 1 and 2 is substantially constant and equal to the width of the treated plate-shaped product 5; also, that the lateral play of the belts is in the main negligible. It is obvious that gaskets, such for instance, as resilient ridges, can be placed transversely along the surfaces of the belts as well as vertically at their edges. If the width of the treated product is smaller than the width of the belts, there can "be placed tightening belts between the conveyor belts, filling out the empty spaces not occupied by the product and thus prevent leakage of the pressure medium through said emptly spaces.

The continuous press according to the embodiment shown in FIGS. 3-5 is similar to the above-described press with regard to the general arrangement of the belts and the pressure chamber. In this case, however, the end walls 25 and 26 do not have a rectangular slit as do the end walls 13 and 14, but rather they have slits shaped as a horizontally placed I. The horizontal parts of said slits serve (as in the preceding case) as apertures for the passage of conveyor belts 1 and 2, whilst the vertical parts of the slits serve as passageways for two endless edge belts 29 and 30 wh ch confine the edges of the conveyor belts 1 and 2 and move at the same speed, the four belts thus forming a space that is closed on all sides around the product. These belts 29 and 30 are resiliently mounted so that they can follow the lateral movements of the belts. Gaskets 31-34 serve to tighten the vertical slits for the edge belts. In addition special longitudinal stationary or movable gaskets may be provided between each of the edge belts 29 and 30 and the conveyor belts.

The type of gasket to be used depends on what pressure it is desired to use and also of the type of product. If the product has even thickness and hence the opening to be sealed has a relatively constant height it is possible to use a gasket that touches the belt under a light friction. FIGS. 6 and 7 show gaskets of this type. In FIG. 6 the end wall 14 of the pressure chamber is provided with a felt gasket 35 which lightly touches the moving belt. In FIG. 7 there is shown a gasket 36 of polytetrafluoroethylene, also in light contact with the belt. FIG. 8 shows a rotating gasket consisting of a wheel 38, in a recess 37, the wheel having tightening ridges 39 for a suitable flexible material. It is also possible to attain a tightening eflect by letting the wall 14 terminate short of the belt, as shown in FIG. 9, whereby the space 40 between the wall and the belt becomes as narrow as possible.

In all of the illustrated cases the tightening means have a fixed position in relation to the end wall 14; however, it is alternatively possible to have the tightening edge, adjustable in the direction normal to the belt, in order to allow for minor variations in the level of the belt.

We claim:

1. A continuous press which comprises a pressure chamber having top, bottom and side walls and first and second end walls at opposite ends of said chamber;

a slit opening in said first end wall;

a slit opening in said second end wall; means for delivering pressure medium from a source thereof to the interior of said chamber; two endless, allochirally disposed conveyor belts having adjacent flights and serving to press and convey between said flights a product in the shape of a plate or the like and to subject said product to a fluid pressure, said two adjacent flights of the belts passing through said slit opening in said first end wall and into and through said pressure chamber that surrounds said flights in the transverse direction and exiting from said chamber through said slit opening in said opposite end wall, said chamber forming a cover around said adjacent flights that is closed in all lateral directions whereby pressure is applied to both of said flights by said pressure medium delivering means. 2. Press as defined in claim 1, in which an edge belt is arranged along each longitudinal edge of each of the conveyor belts, said edge belts being perpendicular to the conveyor belts and substantially covering the opening between the conveyor belts.

References Cited UNITED STATES PATENTS 2,046,047 6/1936 Watkins 156-580 X 2,135,763 11/1938 Nicholson 100-154 X 2,142,932 1/1939 Beard 144-281 3,240,846 3/1966 Voelker 18-4 X 3,167,603 1/1965 Lillie 18-4 X 3,340,795 9/1967 Hartley 100-154 BILLY I. WILHITE, Primary Examiner US. Cl. X.R. 18-4 B 

